FYI, we noticed the below changes on

git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
commit f9b61ff6bce9a44555324b29e593fdffc9a115bc ("drm/i915: Push vblank enable/disable past encoder->enable/disable")


testbox/testcase/testparams: lkp-t410/piglit/performance-igt-069

676fa5721c2eece4  f9b61ff6bce9a44555324b29e5  
----------------  --------------------------  
         %stddev     %change         %stddev
             \          |                \  
      6743 ±  0%    +222.7%      21759 ±  6%  piglit.time.voluntary_context_switches
     73.50 ±  0%    +178.7%     204.84 ±  0%  piglit.time.elapsed_time.max
     73.50 ±  0%    +178.7%     204.84 ±  0%  piglit.time.elapsed_time
         5 ±  8%     -61.9%          2 ±  0%  piglit.time.percent_of_cpu_this_job_got
         0 ±  0%      +Inf%          1 ±  0%  vmstat.procs.b
      6743 ±  0%    +222.7%      21759 ±  6%  time.voluntary_context_switches
     73.50 ±  0%    +178.7%     204.84 ±  0%  time.elapsed_time.max
     73.50 ±  0%    +178.7%     204.84 ±  0%  time.elapsed_time
         5 ±  8%     -61.9%          2 ±  0%  time.percent_of_cpu_this_job_got
       229 ±  5%    +101.5%        461 ±  5%  time.involuntary_context_switches
      1.37 ±  4%     +63.3%       2.24 ±  3%  time.system_time
      9518 ±  0%     -46.1%       5130 ±  5%  vmstat.system.in
     18657 ±  0%     -44.9%      10286 ±  5%  vmstat.system.cs

lkp-t410: Westmere
Memory: 2G




                             piglit.time.elapsed_time

  280 ++--------O-----------------------------------------------------------+
  260 ++            O                                                       |
      |                                                                     |
  240 ++                                                                    |
  220 ++                                                                    |
  200 O+O O O O   O   O OO O O O O O O O O O O O O O O O O OO O O O O O O O O
  180 ++                                                                    |
      |                                                                     |
  160 ++                                                                    |
  140 ++                           *                                        |
  120 ++                           ::                                       |
  100 ++                          : :                                       |
      |                           :  :                                      |
   80 *+*.*.*.*.*.*.*.*.**.*.*.*.*   *.*.*.*.*.*.*                          |
   60 ++--------------------------------------------------------------------+

	[*] bisect-good sample
	[O] bisect-bad  sample

To reproduce:

	apt-get install ruby
	git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
	cd lkp-tests
	bin/setup-local job.yaml # the job file attached in this email
	bin/run-local   job.yaml


Disclaimer:
Results have been estimated based on internal Intel analysis and are provided
for informational purposes only. Any difference in system hardware or software
design or configuration may affect actual performance.


Thanks,
Ying Huang